Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.
AC - Alternating Current, the standard form of electrical current supplied by the utility grid and by most inverters and fuel-powered generators. The polarity (and therefore the direction of current) alternates. In U.S.A., standard voltages for small water pumps are 115V and 230V. Standards vary in different countries. Altitude - Altitude will affect the ability of a suction pump to pull water as the atmospheric pressure is less at higher altitudes. A rough estimate is that it will decrease about 1 foot for every 1000 feet of altitude. If you live at 20,000 feet, you will not be able to use a suction pump. Aquifer - a geologic formation that is water bearing. A geological formation or structure that stores and/or transmits water, such as to wells and springs. Use of the term is usually restricted to those water-bearing formations capable of yielding water in sufficient quantity to constitute a usable supply for people's uses. Artesian water - ground water that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called artesian pressure, and the formation containing artesian water is an artesian aquifer or confined aquifer. -
Booster Pump - A surface pump used to increase pressure in a water line, or to pull from a storage tank and pressurize a water system. See Surface Pump. Borehole - Synonym for water well, especially outside of North America.
- Casing - Plastic or steel tube that is permanently inserted in the well after drilling. Its size is specified according to its inside diameter. The most common in the US is 6", although there are some 4", and old windmills often used 2-1/4". Some larger wells use up to 12".
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- Cable Splice - A joint in electrical cable. A submersible splice must be made using special materials available in kit form.
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- Centrifugal Pump - A pumping mechanism that spins water by means of an "impeller". Water is pushed out by centrifugal force. See also multi-stage. Centrifugal pumps have high flow rates with low suction.
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- Check Valve - A valve that allows water to flow one way but not the other. A foot valve is one example. Electrical analogy: Diode.
Cone of Depression - A cone-shaped depression in the water table around a well or a group of wells. The cone is created by withdrawing ground water more quickly than it can be replaced. -
- Converter - An electronic device for DC power that steps up voltage and steps down current proportionally (or vice-versa). Our Power Point Trackers are an example of a DC-DC converter. Electrical analogy applied to AC: See Transformer. Mechanical analogy: gears or belt drive. This term also means the opposite of inverter when used in describing RV systems.
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- Cubic feet per second (cfs) - a rate of the flow, in streams and rivers, for example. It is equal to a volume of water one foot high and one foot wide flowing a distance of one foot in one second. One "cfs" is equal to 7.48 gallons of water flowing each second. As an example, if your car's gas tank is 2 feet by 1 foot by 1 foot (2 cubic feet), then gas flowing at a rate of 1 cubic foot/second would fill the tank in two seconds.
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- Cut-In Pressure and Cut-Out Pressure - See pressure switch.
- DC - Direct Current, the type of power produced by photovoltaic panels and by storage batteries. The current flows in one direction and polarity is fixed, defined as positive (+) and negative (-). Nominal system voltage may be anywhere from 12 to 180V. See voltage, nominal.
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- DC Motor, Brush-Type - The traditional DC motor, in which small carbon blocks called "brushes" conduct current into the spinning portion of the motor. They are used in DC surface pumps and also in some DC submersible pumps. Brushes naturally wear down after years of use, and may be easily replaced.
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- DC Motor, Brushless - High-technology motor used in centrifugal-type DC submersibles. The motor is filled with oil, to keep water out. An electronic system is used to precisely alternate the current, causing the motor to spin.
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- DC Motor, Permanent Magnet - All DC solar pumps use this type of motor in some form. Being a variable speed motor by nature, reduced voltage (in low sun) produces proportionally reduced speed, and causes no harm to the motor. Contrast: induction motor.
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- Diaphragm Pump - A type of pump in which water is drawn in and forced out of one or more chambers, by a flexible diaphragm. Check valves let water into and out of each chamber.
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- Diode - An electronic semiconductor device that allows current flow in only one direction. Also called a rectifier. The electrical equivalent of a check valve in water.
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- Domestic water use - water used for household purposes, such as drinking, food preparation, bathing, washing clothes, dishes, and dogs, flushing toilets, and watering lawns and gardens. About 85% of domestic water is delivered to homes by a public-supply facility, such as a county water department. About 15% of the Nation's population supply their own water, mainly from wells.
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- Drawdown - Lowering of level of water in a well due to pumping. Recovery Rate - Rate at which groundwater refills the casing after the level is drawn down. This is the term used to specify the production rate of the well.
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- Driller's Log - The written form on which well characteristics are recorded by the well driller. In many states, it is a legal requirement to register all water wells and to send a copy of the log to a state office. This supplies hydrological data and well performance test results to the public and to the well owner.
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- Drip irrigation - a common irrigation method where pipes or tubes filled with water slowly drip onto crops. Drip irrigation is a low-pressure method of irrigation and less water is lost to evaporation than high-pressure.
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- Drop Pipe - The pipe that carries water from a pump in a well up to the surface.
- Efficiency - The percentage of power that gets converted to useful work. Example: An electric pump that is 60% efficient converts 60% of the input energy into work - pumping water. The remaining 40% becomes waste heat.
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- Energy - The product of power and time, measured in Watt-Hours. 1000 Watt-Hours = 1 Kilowatt-Hour (abbreviation: KWH). Variation: the product of current and time is Ampere-Hours, also called Amp-Hours (abbreviation: AH). 1000 watt consumed for 1 hour = 1 KWH.
 Foot Valve - A check valve placed in the water source below a surface pump. It prevents water from flowing back down the pipe and "losing prime". See check valve and priming. It is basically an inline check valve that allow the pump to pull water up, but does not allow the water to flow back down, thus keeping the pipe full of water while the pump is not running. Foot valves come in a variety of shapes, sizes, and materials. The most common materials are brass and plastic.-
- Friction Loss - The loss of pressure due to flow of water in pipe. This is determined by 3 factors: pipe size (inside diameter), flow rate, and length of pipe. It is determined by consulting a friction loss chart available in an engineering reference book or from a pipe supplier. It is expressed in PSI or Feet (equivalent additional feet of pumping).
- Gravity Flow - The use of gravity to produce pressure and water flow. A storage tank is elevated above the point of use, so that water will flow with no further pumping required. A booster pump may be used to increase pressure. 2.3 Verticle Feet = 1 PSI (pound per square inch).
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- Ground water - (1) water that flows or seeps downward and saturates soil or rock, supplying springs and wells. The upper surface of the saturate zone is called the water table. (2) Water stored underground in rock crevices and in the pores of geologic materials that make up the Earth's crust.
- Head - See vertical lift and total dynamic head (TDH). In water distribution, synonym: vertical drop.
- Impeller - See Centrifugal Pump
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- Induction Motor (AC) - The type of electric motor used in conventional AC water pumps. It requires a high surge of current to start and a stable voltage supply, making it relatively expensive to run from by solar power. See Inverter.
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- Inverter - An electronic device that converts DC voltage to high voltage AC power. In solar-electric systems, an inverter may take the 12, 24, or 48 volts DC and convert it to 115 or 230 volts AC conventional household power. Inverters are avalable that will directly convert the output of higher voltage (90 to 400 volts DC) directly into AC power to run a standard AC pump.
- Jet Pump - A surface-mounted centrifugal pump that uses an "ejector" (venturi) device to augment its suction capacity. In a "deep well jet pump", the ejector is down in the well, to assist the pump in overcoming the limitations of suction. (Some water is diverted back down the well, causing an increase in energy use.)
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- Linear Current Booster - A "matching" device to convert the (usually) higher DC voltage from the solar panels into a somewhat lower voltage but higher current for the pump. See pump controller and Maximum Power Point Tracker. Note: Although this term has become generic, its abbreviation "LCB" is a trademark of Bobier Electronics. All of these devices are a type of DC to DC converter.
- Maximum power point tracker - An electronic device that acts as a "transmission" between the PV panels and the pump. Provides the maximum power possible out of the solar array. For detailed information, see our Maximizer section. While an array tracker that follows the sun provides higher efficiency and power in the summer, a MPPT provides the highest gains in winter and/or cold weather, due to the higher PV outputs at colder cell temperatures. Where maximum efficiency is needed, both may be used.
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- Multi-Stage Centrifugal - A centrifugal pump with more than one impeller and chamber, stacked in a sequence to produce higher pressure. Conventional AC deep well submersible pumps and higher power solar submersibles work this way.
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- Open Discharge - The filling of a water vessel that is not sealed to hold pressure. Examples: storage (holding) tank, pond, flood irrigation. Contrast: pressure tank.
- Particle size - the diameter, in millimeters, of suspended sediment or bed material. Particle-size classifications are:
[1] Clay—0.00024-0.004 millimeters (mm);
[2] Silt—0.004-0.062 mm;
[3] Sand—0.062-2.0 mm; and
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- Perforations - Slits cut into the well casing to allow groundwater to enter. May be located at more than one level, to coincide with water-bearing strata in the earth.
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- Permeability--the ability of a material to allow the passage of a liquid, such as water through rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them, whereas unpermeable material, such as clay, don't allow water to flow freely.
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- Photovoltaic - The phenomenon of converting light to electric power. Photo = light, Volt = electricity. Abbreviation: PV.
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- Piston Pump - see sealed piston pump. See also theanimation
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- Pitless Adapter - A special pipe fitting that fits on a well casing, below ground. It allows the pipe to pass horizontally through the casing so that no pipe is exposed above ground where it could freeze. The pump may be installed and removed without further need to dig around the casing. This is done by using a 1 inch threaded pipe as a handle. See well seal.
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- Porosity--a measure of the water-bearing capacity of subsurface rock. With respect to water movement, it is not just the total magnitude of porosity that is important, but the size of the voids and the extent to which they are interconnected, as the pores in a formation may be open, or interconnected, or closed and isolated. For example, clay may have a very high porosity with respect to potential water content, but it constitutes a poor medium as an aquifer because the pores are usually so small.
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- Positive Displacement Pump - Any mechanism that seals water in a chamber, then forces it out by reducing the volume of the chamber. Examples: piston (including jack), diaphragm, rotary vane. Used for low volume and high lift. Contrast with "centrifugal". Synonyms: volumetric pump, force pump.
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- Power - The rate at which work is done. It is the product of Voltage times Current, measured in Watts. 1000 Watts = 1 Kilowatt. An electric motor requires approximately 1 Kilowatt per Horsepower (after typical efficiency losses). 1 Kilowatt for 1 Hour = 1 Kilowatt-Hour (KWH).
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- Pressure - The amount of force applied by water that is either forced by a pump, or by the gravity. Measured in pounds per square inch (PSI). PSI = vertical lift (or drop) in Feet / 2.31, or .43 PSI per foot.
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- Pressure Switch - An electrical switch actuated by the pressure in a pressure tank. When the pressure drops to a low set-point (cut-in) it turns a pump on. At a high point (cut-out) it turns the pump off.
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- Pressure Tank - A fully enclosed tank with an air space inside. As water is forced in, the air compresses. The stored water may be released after the pump has stopped. Most pressure tanks contain a rubber bladder to capture the air, synonym: captive air tank. Sizes range from less than 1 gallon up to several hundred. 25 to 120 gallons are the most common sizes.
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- Pressure Tank Precharge - The pressure of compressed air stored in a captive air pressure tank. A reading should be taken with an air pressure gauge (tire gauge) with water pressure at zero. The air pressure is then adjusted to about 3 PSI lower than the cut-in pressure (see Pressure Switch). If precharge is not set properly, the tank will not work to full capacity, and the pump will cycle on and off more frequently.
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- Priming - The process of hand-filling the suction pipe and intake of a surface pump. Priming is generally necessary when a pump must be located above the water source. A "self-priming" pump is able to draw some air suction in order to prime itself, at least in theory. See foot valve.
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- Pulsation Damper - A device that absorbs and releases pulsations in flow produced by a piston or diaphragm pump. Consists of a chamber with air trapped within it. A "shock absorber" to prevent water hammers and to provide a more even pressure.
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- Pump Controller - An electronic device which varies the voltage and current of a PV array to match the needs of an array-direct pump. It allows the pump to start and to run under low sun conditions without stalling. Electrical analogy: variable transformer. Mechanical analogy: automatic transmission. See Linear Current Booster and Maximum Power Point Tracker.
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- Pump Jack - A deep well piston pump. The piston and cylinder is submerged in the well water and actuated by a rod inside the drop pipe, powered by a motor at the surface. This is an old-fashioned system still used for extremely deep wells, including solar pumps as deep as 1000 feet. In solar powered systems, a DC motor replaces the windmill.
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- PV - The common abbreviation for photovoltaic.
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- PV Array - A group of PV (photovoltaic) modules (also called panels) arranged to produce the voltage and power desired.
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- PV Array-Direct - The use of electric power directly from a photovoltaic array, without storage batteries to store or stabilize it. Most solar water pumps work this way, utilizing a tank to store water.
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- PV Cell - The individual photovoltaic device. The most common PV modules are made with 33 to 36 silicon cells each producing about 1/2 volt.
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- PV Module - An assembly of PV cells framed into a weatherproof unit. Commonly called a "PV panel" or solar panel. See PV Array. Most solar crystalline solar panels have 36 cells, most thin film panels have 33.
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- Radius of influence - the radial distance from the center of a well bore to the point where there is no lowering of the water table or potentiometric surface.
Recharge area - area in which water reaches the zone of saturation by surface infiltration. An area in which there are downward components of hydraulic head in the aquifer. Infiltration moves downward into the deeper parts of an aquifer in a recharge area.
- Sealed Piston Pump - A type of pump in which water is drawn in and forced out of a chamber by a piston mechanism. The pistons have a very short stroke, allowing the use of flexible gaskets to seal water out of the piston mechanism. Check valves let water into and out of the chamber.
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- Safety Rope - Plastic rope used to suspend the pump, primarily in case of pipe breakage.
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- Static Water Level - Depth to the water surface in a well under static conditions (not being pumped). May be subject to seasonal changes or lowering due to depletion.
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- Submersible Cable - Electrical cable designed for in-well submersion.
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- Size (in USA) is specified by American Wire Gauge (AWG), in which a higher number indicates smaller wire. Elsewhere it is specified in millimeters. The specification "two-wire plus ground" will indicate three wires (conductors) in the cable. It is connected to a pump by splicing.
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- Submersible Pump - A motor/pump combination designed to be placed entirely below the water surface.
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- Suction Lift - Applied to surface pumps: Vertical distance from the surface of the water in the source, to a pump located above surface pump located above. This distance is limited by physics to around 20 feet at sea level (subtract 1 ft. per 1000 ft. altitude) and should be minimized for best results.
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- Submergence - Applied to submersible pumps: Distance beneath the static water level, at which a pump is set. Synonym: immersion level. Total Dynamic Head - vertical lift + friction loss in piping (see friction loss).
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- Surface Pump - A pump that is not submersible. It must be placed no more than about 18 ft. above the surface of the water in the well. See priming and jet pump.
- Tracker - A mounting rack for a PV array that automatically tilts to follow the daily path of the sun through the sky. A "tracking array" will produce more energy through the course of the day, than a "fixed array" (non-tracking) particularly during the long days of summer. Energy gain varies from 10-25%. When used with a Maximum Power Point Tracker, total yearly gains typically approach 30%.
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- Transformer - An electrical device that steps up voltage and steps down current proportionally (or vice-versa). Transformers work with AC only. For DC, see Converter. Mechanical analogy: gears or belt drive.
- Utility Grid - Commercial electric power distribution system. Synonym: Mains.
- Vane Pump - (Rotary Vane) A positive displacement mechanism used in low volume high lift surface pumps and booster pumps. Durable and efficient, but requires cleanly filtered water due to its mechanical precision.
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- Vertical Lift - The vertical distance that water is pumped. This determines the pressure that the pump pushes against. Total vertical lift = vertical lift from surface of water source up to the discharge in the tank + (in a pressure system) discharge pressure. Synonym: static head. Note: Horizontal distance does NOT add to the vertical lift, except in terms of pipe friction loss. NOR does the volume (weight) of water contained in pipe or tank. Submergence of the pump does NOT add to the vertical lift in the case of a centrifugal type pump. In the case of a positive displacement pump, it may add to the lift somewhat.
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- Voltage - The measurement of electrical potential. Analogy: Pressure in a water pipe.
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- Voltage Drop - Loss of voltage (electrical pressure) caused by the resistance in wire and electrical devices. Proper wire sizing will minimize voltage drop, particularly over long distances. Voltage drop is determined by 4 factors: wire size, current (amps), voltage, and length of wire. It is determined by a consulting wire sizing chart or formula available in various reference tests. It is expressed as a percentage. Water analogy: Friction Loss in pipe.
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- Voltage, Nominal - A way of naming a range of voltage to a standard. Example: A "12 Volt Nominal" system may operate in the range of 11 to 15 Volts. We call it "12 Volts" for simplicity.
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- Voltage, Open Circuit - The voltage of a PV module or array with no load (when it is disconnected). A "12 Volt Nominal" PV module will produce about 18-20 Volts open circuit. Abbreviation: Voc. Note that some of the so-called "self regulating" modules produce much lower voltages and are not generally suited for water pumping.
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- Voltage, Peak Power Point - The voltage at which a photovoltaic module or array transfers the greatest amount of power (watts). A "12 Volt Nominal" PV module will typically have a peak power voltage of around 17 volts. A PV array-direct solar pump should reach this voltage in full sun conditions. In a higher voltage array, it will be a multiple of
this voltage. Abbreviation: Vpp. See also Maximum Power Point Tracker.
- Water Table - The level at which the water stays. The very top of the zone of saturation. Water can also be found a few centimeters above this level water due to capillary action. In the presence of a pumping well, the water table drops near the well. This situation is called drawdown. Under some conditions, a perched water table may exist. This occurs when the water percolation is interrupted by another confining layer above the "main" one.
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- Wellhead - Top of the well, at ground level.
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- Wellhead protection area - a designated area around a public water supply well(s) that is to be protected from contaminants that may adversely affect human health.
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- Well Seal - Top plate of well casing that provides a sanitary seal and support for the drop pipe and pump. Alternative: See Pitless Adapter
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- Zone of saturation - the space below the water table in which all the interstices (pore spaces) are filled with water. Water in the zone of saturation is called groundwater.
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